Move ScorerAccountingForInFlightHtlcs to router + make public

We move it to router instead of scoring because it pairs with the InFlightHtlcs
struct in router and is useful for custom Router trait implementations

Author: valentinewallace

lightning-invoice/src/payment.rs

@@ -731,15 +731,15 @@ where
 mod tests {
 	use super::*;
 	use crate::{InvoiceBuilder, Currency};
-	use crate::utils::{ScorerAccountingForInFlightHtlcs, create_invoice_from_channelmanager_and_duration_since_epoch};
+	use crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch;
 	use bitcoin_hashes::sha256::Hash as Sha256;
 	use lightning::ln::PaymentPreimage;
 	use lightning::ln::channelmanager;
 	use lightning::ln::features::{ChannelFeatures, NodeFeatures};
 	use lightning::ln::functional_test_utils::*;
 	use lightning::ln::msgs::{ChannelMessageHandler, ErrorAction, LightningError};
 	use lightning::routing::gossip::{EffectiveCapacity, NodeId};
-	use lightning::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, Router};
+	use lightning::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, Router, ScorerAccountingForInFlightHtlcs};
 	use lightning::routing::scoring::{ChannelUsage, LockableScore, Score};
 	use lightning::util::test_utils::TestLogger;
 	use lightning::util::errors::APIError;

lightning-invoice/src/utils.rs

@@ -15,9 +15,9 @@ use lightning::ln::channelmanager::{ChannelDetails, ChannelManager, PaymentId, P
 use lightning::ln::channelmanager::{PhantomRouteHints, MIN_CLTV_EXPIRY_DELTA};
 use lightning::ln::inbound_payment::{create, create_from_hash, ExpandedKey};
 use lightning::ln::msgs::LightningError;
-use lightning::routing::gossip::{NetworkGraph, NodeId, RoutingFees};
-use lightning::routing::router::{InFlightHtlcs, Route, RouteHint, RouteHintHop, RouteParameters, find_route, RouteHop, Router};
-use lightning::routing::scoring::{ChannelUsage, LockableScore, Score};
+use lightning::routing::gossip::{NetworkGraph, RoutingFees};
+use lightning::routing::router::{InFlightHtlcs, Route, RouteHint, RouteHintHop, RouteParameters, find_route, RouteHop, Router, ScorerAccountingForInFlightHtlcs};
+use lightning::routing::scoring::{LockableScore, Score};
 use lightning::util::logger::Logger;
 use secp256k1::PublicKey;
 use core::ops::Deref;
@@ -627,54 +627,6 @@ where
 	fn inflight_htlcs(&self) -> InFlightHtlcs { self.compute_inflight_htlcs() }
 }
 
-
-/// Used to store information about all the HTLCs that are inflight across all payment attempts.
-pub(crate) struct ScorerAccountingForInFlightHtlcs<'a, S: Score> {
-	scorer: &'a mut S,
-	/// Maps a channel's short channel id and its direction to the liquidity used up.
-	inflight_htlcs: InFlightHtlcs,
-}
-
-impl<'a, S: Score> ScorerAccountingForInFlightHtlcs<'a, S> {
-	pub(crate) fn new(scorer: &'a mut S, inflight_htlcs: InFlightHtlcs) -> Self {
-		ScorerAccountingForInFlightHtlcs {
-			scorer,
-			inflight_htlcs
-		}
-	}
-}
-
-#[cfg(c_bindings)]
-impl<'a, S:Score> lightning::util::ser::Writeable for ScorerAccountingForInFlightHtlcs<'a, S> {
-	fn write<W: lightning::util::ser::Writer>(&self, writer: &mut W) -> Result<(), lightning::io::Error> { self.scorer.write(writer) }
-}
-
-impl<'a, S: Score> Score for ScorerAccountingForInFlightHtlcs<'a, S> {
-	fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage) -> u64 {
-		if let Some(used_liquidity) = self.inflight_htlcs.used_liquidity_msat(
-			source, target, short_channel_id
-		) {
-			let usage = ChannelUsage {
-				inflight_htlc_msat: usage.inflight_htlc_msat + used_liquidity,
-				..usage
-			};
-
-			self.scorer.channel_penalty_msat(short_channel_id, source, target, usage)
-		} else {
-			self.scorer.channel_penalty_msat(short_channel_id, source, target, usage)
-		}
-	}
-
-	fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) { unreachable!() }
-
-	fn payment_path_successful(&mut self, _path: &[&RouteHop]) { unreachable!() }
-
-	fn probe_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) { unreachable!() }
-
-	fn probe_successful(&mut self, _path: &[&RouteHop]) { unreachable!() }
-}
-
-
 #[cfg(test)]
 mod test {
 	use core::time::Duration;

lightning/src/routing/router.rs

@@ -56,6 +56,66 @@ pub trait Router {
 	fn notify_payment_probe_failed(&self, path: &[&RouteHop], short_channel_id: u64);
 }
 
+/// [`Score`] implementation that factors in in-flight HTLC liquidity.
+///
+/// Useful for custom [`Router`] implementations to wrap their [`Score`] on-the-fly when calling
+/// [`find_route`].
+///
+/// [`Score`]: crate::routing::scoring::Score
+pub struct ScorerAccountingForInFlightHtlcs<'a, S: Score> {
+	scorer: &'a mut S,
+	// Maps a channel's short channel id and its direction to the liquidity used up.
+	inflight_htlcs: InFlightHtlcs,
+}
+
+impl<'a, S: Score> ScorerAccountingForInFlightHtlcs<'a, S> {
+	/// Initialize a new `ScorerAccountingForInFlightHtlcs`.
+	pub fn new(scorer: &'a mut S, inflight_htlcs: InFlightHtlcs) -> Self {
+		ScorerAccountingForInFlightHtlcs {
+			scorer,
+			inflight_htlcs
+		}
+	}
+}
+
+#[cfg(c_bindings)]
+impl<'a, S:Score> Writeable for ScorerAccountingForInFlightHtlcs<'a, S> {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> { self.scorer.write(writer) }
+}
+
+impl<'a, S: Score> Score for ScorerAccountingForInFlightHtlcs<'a, S> {
+	fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage) -> u64 {
+		if let Some(used_liquidity) = self.inflight_htlcs.used_liquidity_msat(
+			source, target, short_channel_id
+		) {
+			let usage = ChannelUsage {
+				inflight_htlc_msat: usage.inflight_htlc_msat + used_liquidity,
+				..usage
+			};
+
+			self.scorer.channel_penalty_msat(short_channel_id, source, target, usage)
+		} else {
+			self.scorer.channel_penalty_msat(short_channel_id, source, target, usage)
+		}
+	}
+
+	fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
+		self.scorer.payment_path_failed(path, short_channel_id)
+	}
+
+	fn payment_path_successful(&mut self, path: &[&RouteHop]) {
+		self.scorer.payment_path_successful(path)
+	}
+
+	fn probe_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
+		self.scorer.probe_failed(path, short_channel_id)
+	}
+
+	fn probe_successful(&mut self, path: &[&RouteHop]) {
+		self.scorer.probe_successful(path)
+	}
+}
+
 /// A data structure for tracking in-flight HTLCs. May be used during pathfinding to account for
 /// in-use channel liquidity.
 pub struct InFlightHtlcs(